The invention relates to an axial flux focusing torque sensor. Non-contacting torque sensors generate output voltage corresponding to the relative angular displacement between an upper and lower shaft connected by a torsion bar. From the output voltage, a control system measures a steering assist value provided to the vehicle. Conventional torque sensors typically rely on a radial flux focusing magnet arrangements, where radially oriented magnets are placed in the upper rotor. Lower rotors are placed radially outside the upper rotor, increasing the overall diameter of the torque sensor. Additionally, the placement of the lower rotors radially outside the upper rotor introduces inherent noise in the sensor output.
Alternatively, torque sensors with axially magnetized magnets in the upper rotor and concentric coaxial ferromagnetic rings of different radii in the lower rotor have a large variation of the radial flux density between the ferromagnetic rings. This type of design is highly sensitive to the placement of a magnetic flux sensing element in between the ferromagnetic rings.